1. Field of the Invention
The present invention relates to an abnormality determination system and an abnormality determination method for a processing apparatus.
2. Description of Related Art
In a semiconductor device manufacturing line, a photolithography technique is generally used to form a resist pattern in the surface of a substrate to be processed, such as a semiconductor wafer or an LCD substrate. The photolithography technique forms a predetermined resist pattern in the surface of the substrate by performing a sequence of process steps including: a resist coating step of applying a resist solution onto the surface of a substrate; an exposure step of exposing a pattern in the resist film formed; and a developing step of supplying a developer to the substrate after the exposure process. The sequential steps are performed in a resist coating/developing apparatus having various processing units for processing a substrate, a transport unit for transporting the substrate, etc.
In such a resist coating/developing apparatus, a plurality of substrates are transported and processed in a successive manner. Therefore, in the event of the occurrence of an abnormality in a processing unit of the apparatus, the abnormality should be detected promptly. If a substrate, which has undergone abnormal processing, is so subjected to later processing, a waste of a processing liquid, for example, will be produced. As an apparatus for determining the occurrence of an abnormality, a monitoring apparatus is known which includes a data acquiring section for acquiring data from sensors installed in various processing units, a data pickup section for picking up useful data from the data acquired by the data acquiring section, an abnormal data extracting section for extracting abnormal data from the useful data picked up by the data pickup section, and an abnormality determining section for correlating the abnormal data extracted by the abnormal data extracting section with failure information (see e.g. Japanese Patent Laid-Open Publication No. 2000-243678 (patent document 1)).
The abnormal data extracting section uses preset upper and lower constant threshold values when extracting abnormal data from the useful data picked up by the data pickup section. The abnormality determining section determines whether a change in data, which has been determined to be abnormal by the abnormal data extraction section, is related to failure information obtained in a later inspection step.
As described above, in the monitoring apparatus described in patent document 1, the abnormal data extraction section extracts and determines an abnormality based on the upper and lower constant threshold values. Accordingly, the monitoring apparatus cannot extract and determine the occurrence of an abnormality in processing, e.g. in the timing of processing, if the data value, corresponding to the abnormality, lies between the upper and lower constant threshold values. This leads to a lowering of the accuracy of abnormality determination.